As a conventional terminal structure for large current, for example, an electric socket (female terminal) is known in which a tubular terminal (spring contact) is enclosed in a main case (female terminal main body) (see Patent Document 1).
As shown in FIG. 12A, in this type of terminal structure, a spring (spring contact) 503 enclosed in a female terminal 501 is designed so as to have, at a contracted portion 507, an innermost diameter smaller than the outer diameter of a counterpart male terminal 505.
As shown in FIGS. 12B and 12C, in the female terminal 501, when the male terminal 505 is inserted, the contracted portion 507 of the spring 503 is deformed in the diameter increasing direction.
As shown in FIG. 12C, according to this terminal structure, by the elastic deformation of the spring 503 caused when the male terminal is inserted, a contact load is obtained to thereby secure an electrically stable contact.